Numerous other problems undermine their conclusions. Their CPS reconstruction screens proxies by calibration-period correlation, a procedure known to generate “hockey sticks” from red noise (4). The proportion of proxies with “significant” correlation to gridcell temperature is overestimated by comparison to two (not one) gridcells, inclusion of “proxies” incorporating instrumental temperatures, and underadjustment for autocorrelation.

Their non-dendro network uses some data with the axes upside down, e.g., Korttajarvi sediments, which are also compromised by agricultural impact (M. Tiljander, personal communication), and uses data not qualified as temperature proxies (e.g., speleothem δ13C).

Although Mann et al. purport to “follow the suggestions” of ref. 5, they employed “strip-bark” dendrochronologies despite the recommendation of ref. 5 that these chronologies be “avoided” and fail to observe the caveats of ref. 5 that negative CE statistics indicate unreliable results.

Physical and social well-being in old age are linked to self-assessments of life worth, and a spectrum of behavioral, economic, health, and social variables may influence whether aging individuals believe they are leading meaningful lives.